268 



THE YOUNG NATURALIST. 



those tiny leaf-mining larvse — Lithcolleiis quiuqiieguttella, for instance — 

 which lives inside the leaves of the dwarf sallow in July and September ; or 

 Lithocolletis schreeberella, which mines the under side of elm leaves at the 

 same time, and both of which are of such tiny dimensions that the moths 

 they develope into do not expand more than a quarter of an inch ? If we 

 assume that all internal feeding larvae are formed on the same model, then 

 we may compare these minute Lithocolletis larvse with the caterpillar of the 

 Goat moth. Now Lyonnet found that the number of muscles in the larvse 

 of Cossus ligniperda amounted to as many as 4000 ; of which 288 were in 

 the head, 1647 in the body, and 2186 around the intestines, so that if a 

 Lithocolletis larva has anything like the same number the size of each is 

 utterly beyond our conception. 



Truly the microscopic study of insects and their structure furnishes a wide 

 field for investigation, and a vast deal yet remains to be learned respecting 

 the comparative anatomy of this portion of creation. I cannot forbear once 

 more urging my entomological readers to devote some of their winter evenings 

 to this works. To dissect an insect requires, I am well aware, an infinite 

 amount of patience, yet almost any species will well repay the trouble be- 

 stowed upon it. 



Insects may be rendered sufficiently transparent to permit of the internal 

 parts being microscopically examined, by soaking them in liquor potassse for 

 about a fortnight, and subsequently in alcohol, then in ether, and lastly in 

 turpentine. The details of the process, by which entire insects may be made 

 beautifully transparent so that they may be mounted in balsam without pres- 

 sure, were given in a recent number of "The Journal of Microscopy," and to 

 this I refer such of my readers as desire information on the subject. 



How wonderfully complicated the structure of the well known cockroach 

 is, the illustrated articles on the subject which appeared in last year's " Science 

 Gossip" abundantly show, and those who desire to study insect anatomy can- 

 not do better than take them as a guide. But I must not enlarge further on 

 this theme, so with this recommendation to my young entomological to work 

 a little with the microscope on winter evenings, I bring to a close these 

 papers on The Entomological Year. 



Cambridge. 



